Amazon UK's product page for Star Wars: Heir to the Jedi by Kevin Hearne now features a synopsis of the novel. Check it out below (via Star Wars Books UK):

The Galactic Civil War rages on after the destruction of the Death Star and Luke Skywalker struggles to learn more about the Force without the aid of Obi-Wan Kenobi-or indeed without any aid at all. But the few memories he has of Obi-Wan's instruction point the way to a stronger control of the Force, and he is encouraged to pursue it by a new friend in the Alliance. When Luke, R2-D2 and his new ally are tasked with liberating a valuable asset from the Empire and delivering her to a safe planet where she can aid the Alliance, their journey across the galaxy is fraught with peril-and opportunities for Luke to discover the mysteries of the Force.

Heir to the Jedi, which is set in the Rebellion era, will be released in January 2015.